Automatic gun with ejection actuated rammer

ABSTRACT

An ammunition receiver is axially aligned with a reciprocating barrel and is separated from the barrel by a pivotable deflector. As the barrel is driven forwardly by springs loaded by recoil forces from the previous firing, a round of ammunition is propelled forwardly by a pneumatically driven rammer. The round pivots the deflector out of its path and is then locked in the barrel and fired. The recoil forces from the firing first overcome the forward momentum of the barrel and then drive the barrel rearwardly, during which time the expended cartridge is ejected rearwardly where it is deflected transversely through an ejection port by the deflector. Movement of the deflector caused by impact of the ejecting cartridge actuates the rammer to drive another round of ammunition forwardly into the barrel. A first round pulse and delay valve initially controls actuation of the rammer and the delayed release of the barrel from its sear in firing the first of a series of rounds.

United States Patent 72] inventors Eugene M. Stoner Port Clinton; George W. Wight, Jr., Oak Harbor, both of, Ohio [21] Appl. No. 858,398

[22] Filed Sept. 16, 1969 [45] Patented June 15, 1971 [73] Assignee Oberlikon-Buehrle Holding A.G. Zurich- Oerlikon Zurich, Switzerland [54] AUTOMATIC GUN WITH EJECTION ACTUATED RAMMER Primary ExaminerBenjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Attorney- Fowler, Knobbe & Martens ABSTRACT: An ammunition receiver is axially aligned with a reciprocating barrel and is separated from the barrel by a pivotable deflector. As the barrel is driven forwardly by springs loaded by recoil forces from the previous firing, a round of ammunition is propelled forwardly by a pneumatically driven rammer. The round pivots the deflector out of its path and is then locked in the barrel and fired. The recoil forces from the firing first overcome the forward momentum 17 Claims, 25 Drawing Figs. I

of the barrel and then drive the barrel rearwardly, during [52] US. Cl 89/47 which time the expended cartridge is ejected rearwardly P- Cl 17/16 where it is deflected transversely through an ejection port by [50] Field Of Search 89/33 R, 33 the deflector Movement of the deflector caused by impact f 33 33 33 45, 47 the ejecting cartridge actuates the rammer to drive another 56 Re ences Cited round of ammunition forwardly into the barrel. A first round l r pulse and delay valve initially controls actuation of the UNITED STATES PATENTS rammer and the delayed release of the barrel from its sear in 2,594,770 4/1952 Hammar et al. 89/33(A) firing the first ofa series of rounds.

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PATENTED JUN] 5 IQYI SHEET 0 3 OF PATENTEUJUHISIBYI 3,584,532

SHEET OSUF 12 INVENTORS:

gwez W. mas m AUTOMATIC GUN WITH EJECTION ACTUATEI) RAMMER RELATED APPLICATION This invention is related to an application entitled Automatic Gun, Ser. No. 662,614, filed Aug. 23, 1967 by Eugene M. Stoner, now US Pat. No. 3,500,718, issued Mar. 17, 1970.

BACKGROUND OF THE INVENTION This invention relates to an automatic gun or cannon, particularly adapted to provide a high rate of fire for relatively large caliber ammunition.

In the earlier application referenced above, a reciprocating gun barrel is driven by springs loaded by recoil forces from the previous firing. An ammunition receiver located to the rear of the barrel and aligned with the barrel guides a round of ammunition toward the barrel chamber as the round is propelled by a lightweight rammer mounted on the receiver. The rammer is driven by a spring which is loaded by and released by movement of the barrel. An expended cartridge is ejected rearwardly and then deflected transversely out an ejection port by a deflector while the rammer is driving the succeeding round forwardly towards the barrel firing chamber. The deflector prevents the ejected cartridge from striking the succeeding round. Overlapping the rammer feeding step with the ejection operation provides high-speed operation. This is in contrast with the slower more conventional reciprocating bolt operation of other weapons.

While the foregoing arrangement is extremely fast and quite reliable, there is some possibility that a jamming problem could arise in view of the rammer cycle being triggered by the barrel. As stated, a round of ammunition is driven forwardly by the rammer when the barrel has reached a certain point in its previous cycle. At this point the expended cartridge of the previous firing is in the process of being ejected to make room for the succeeding round. On rare occasions, an expended cartridge may stick in the barrel firing chamber instead of properly ejecting. If this unusual condition should occur, the succeeding shell would, nevertheless, be driven forwardly by the rammer toward the firing chamber. As a result, the mechanism would likely be jammed and possibly damaged. It would then be necessary to stop operation and correct the malfunction. In combat operations such delay could, of course, be critical.

Accordingly, as an additional safety feature, it is highly desirable that such gun be constructed to prevent such a situation. It is also desirable that the rammer be driven in a positive manner by means which are independent from the movement of the barrel.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a gun having a barrel and a rammer for driving a round of ammunition into the barrel firing chamber with the movement of an expended cartridge in the process of being ejected being utilized to trigger the release of the rammer. Thus, the succeeding round of ammunition will not be driven toward the barrel until and unless positive indication is received that the previous expended cartridge is being ejected. This ensures that the firing chamber in the barrel will be open to receive the succeeding round. In a preferred form of this invention, a deflector positioned at the forward end of the rammer, adjacent the cartridge ejection port is in the path of the cartridge being ejected so that it deflects the cartridge outwardly. In the process the deflector is moved, and this movement of the deflector in turn is used to trigger the release of the rammer.

Preferably, the rammer is pneumatically driven, and the application of air pressure is controlled by a valve operated by movement of the deflector. The rammer is returned by a spring with the result that the rammer operation is independent from movement of the barrel. This pneumatic system is used in conjunction with a pneumatically driven mechanism which feeds ammunition into the receiver.

There is also provided a first round pulse and delay valve which first releases the rammer to drive a round of ammunition toward the firing chamber of the barrel as soon as the gun is placed into operation and then releases the barrel from a rear spring loaded position slightly after the rammer is released. This insures the proper initial timing relationship. So long as the gun is retained in firing position, this valve then remains in a barrel release position while no longer controlling the rammer operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top plan view of a gun constructed in accordance with the invention;

FIG. 2 is a perspective view of the rear main portion of the 8"";

FIG. 3 is a side cross-sectional view of the portion of the gun illustrated in FIG. 2;

FIG. 4a is an enlarged cross-sectional view of the rear portion of the gun viewed in FIG. 3;

FIG. 4b is an enlarged cross-sectional view of the central portion of the gun viewed in FIG. 3;

FIG. 5 is a cross-sectional view on line 5-5 of FIG. 4a illustrating the rammer cylinder and a portion of the feed mechanism;

FIG. 6 is a cross-sectional view on line 6-6 of FIG. 4a showing further portions of the rammer assembly and the feed mechanism;

FIG. 7 is a cross-sectional view on line 7-7 of FIG. 4a looking rearwardly to illustrate portions of the rammer assembly and the reed mechanism;

FIG. 8 is a cross-sectional view on line 8-8 of FIG. 4a showing a portion of the barrel sear mechanism;

FIG. 9 is a cross-sectional view on line 9-9 of FIG. 4b showing the breech assembly of the gun;

FIG. 10 is a cross-sectional view on line 10-10 of FIG. 4b showing additional structure of the breech assembly;

FIG. 11 is an enlarged perspective view of the breech assembly;

FIG. 12 is an enlarged cutaway perspective view showing a portion of the breech block cam assembly and the barrel sear;

FIG. 13 is an enlarged perspective view of the cartridge ejection mechanism;

FIG. 14 is a top plan view showing the mounting of the deflector;

FIG. 15 is a cross-sectional view on line 15-15 of FIG. 14 further illustrating the deflector mounting;

FIG. 16 and 17 are cross-sectional views on the lines 16-16 and 17-17 respectively of FIG. 15 further illustrating the deflector mounting;

FIGS. I8-23 are side elevational views, partially in section of the main portion of the gun illustrating its operation; and

FIG. 24 is a diagram of the pneumatic control system for the gun.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGS. 13, the gun may be considered to have several major assemblies including a barrel assembly 12; a breech ring assembly 14 attached to the rear of the barrel assembly; a breech block cam assembly 16 in which the combined barrel assembly and breech ring assembly are mounted for axial reciprocation; a drive spring assembly 17 connected between the breech block cam assembly and the combined barrel breech ring assembly; a rammer assembly located to the rear of the breech block cam assembly 16 and axially aligned with the barrel assembly 13 for receiving a round of ammunition and for propelling the round forwardly into the barrel; an ammunition feed mechanism 20; a buffer-charger assembly 22; and a pneumatic control system 23 (FIG. 24).

The rear of the gun may be secured with a variety of mounts, depending on the use for the weapon. No particular mount is described herein but for purposes of illustration, the breech block cam assembly 16, the rammer assembly 18, and the buffer-charger assembly 22 are removably attached to a supporting housing 24 which may be mounted for movement in suitable trunnions (not shown).

IRAMMER ASSEMBLY a. Receiver The rammer assembly will be described with particular reference to FIG. 40 as well as with reference to the various sections illustrated in FIGS. -8. Included in the rammer assembly 18 is a tubular ammunition receiver 16 having an inner diameter adequate to receive a round of ammunition 28 shown positioned within the tube. While the gun can be made in a variety of sizes, the illustrated embodiment is designed for 35 mm. ammunition. As seen from FIG. 6, the receiver 26 has openings 30 on either side for receiving ammunition from the ammunition feed mechanism 20. The central top portion of the receiver 26 is closed by an upper plate 32 of the feed mechanism 20. The rear of the receiver 26 is open, even though the ammunition enters from the sides.

A holding pawl 34 is pivotally mounted on a pin 35 secured to the rear upper portion of the ammunition receiver 26. The lower portion of the pawl 34 is urged by a pawl spring 36 clockwise as viewed in FIG. 4a to extend downwardly through an opening 37 in the upper wall of the rammer tube 26. The lower end of the pawl 34 engages the rear of the round of ammunition 28 to prevent the round from sliding rearwardly in the tube.

b. Deflector The forward end of the receiver 26 is tapered rather sharply so that the upper portion is considerably shorter than the lower portion. This creates an outlet or ejection port 27 between the tube and the breech-block cam assembly 16 through which spent cartridges are ejected. A cartridge or case deflector 38 having a forward curved surface extends completely across the front end of the receiver 26 and also extends somewhat above the receiver. This deflector is pivotally and slideably mounted on the forward end of the receiver to form a variety of functions.

Referring now to FIGS. 14-17, it can be seen that the deflector 38 is formed with a large rearwardly extending tongue 38a with the rear portion of the tongue being of slightly reduced thickness, such that a pair of rearwardly facing shoulders 38b are formed. The rearwardmost portion of the tongue 38a is notched forming a downwardly facing sloping cam surface 380. The lower portion 38d of the tongue 380 extends downwardly through an opening 42 in the receiver slightly spaced from the round of ammunition 28 but in the path of the round as it is moved forwardly by the rammer.

A pin 39 extends transversely through the tongue 38a and the ends ofthe pin extend into mating holes in a pair of mating slideable blocks 40. Each block is formed with a recess 40a on its inner side within which is positioned a coil spring 42 mounted on the pin 39. One end of each spring extends vertically and engages the rearwardly facing shoulders 38b of the tongue 38a. The other end of each spring engages the bottom surface of the recess 40a in a slideable block. The springs 41 are oriented so that the deflector is urged to pivot clockwise into the position illustrated in FIGS. 4a and 15, i.e., into the position obstructing the patch between the rammer tube and the firing chamber. The deflector is, of course, movable in the opposite direction against the resistance of the springs so as to be clear of the path between the rammer tube and the firing chamber.

The slideable blocks 40 are formed with depending portions 40b which extend into the opening 42 in the receiver 26. As can be seen from FIGS. 14 and 15, the length of the blocks and the depending portions is slightly less than the length of the opening 42 in the receiver; and consequently, the blocks may be slid that limited amount on the upper surface of the receiver with the ends of the opening marking the limits of the movement. The slideable blocks are retained in slideable engagement with the receiver by means of a clamp 43 having somewhat of a square C-shape when viewed from above as in FIG. I4. The distance between the arms of the clamp is sufficient to receive the upper portions of the blocks 40 together with the pin 39 carrying the springs and the deflector tongue. The lower portion of the space between the clamp arms is undercut on each side to form rearwardly extending grooves 43a into which extend outwardly extending ribs 400 formed on blocks. As can be seen from FIG. 17, the ribs 400 fit snugly within the grooves 43a so that by securing the clamp to the receiver, the blocks are prevented from moving upwardly and transversely; and as already explained, the rearward and forward movement of the blocks is limited by the opening 42 in the receiver.

As seen from FIG. 15, the rear portion of the C-shaped clamp, which extends completely across the receiver is formed with an opening 43b for receiving a control rod 64, thus forming a bearing for the rod which will be subsequently described in greater detail.

c. Rammer Housing and Backplate Assembly As can be seen from the cross-sectional views in FIGS. 5 and 6, an elongated U-shaped housing 44 having a bottom wall 44a and sidewalls 44b is positioned beneath the ammunition receiver 26. The upper ends of the housing sidewalls 44b are attached by suitable means to lugs 26b depending from the receiver 26. As seen in FIG. 4a, a backplate assembly 48 fits within the end of the housing 44 and includes a rectangular backplate 49 attached to the rammer assembly by two quickdisconnect pins 51 which extend through backplate 49 and the sidewalls 44b of the rammer housing 44.

A rammer tube 50 extends through an opening in the backplate 49 and into the housing 44, being attached to the plate in cantilever fashion by a pair of nuts 52 threaded onto the tube 50 and abutting the backplate 49. Slideably mounted on the rammer tube 50 is a cylindrical rammer piston 54 having a closed forward end. The tolerance between the rammer tube and the rammer cylinder is sufficiently close, such that the cylinder may be fired forwardly by applying pressurized fluid through the rammer tube against the inner closed end of the rammer piston. The outer surface of the rammer piston 54 is formed with an enlarged portion 54a spaced slightly from the rear end of the piston. A return spring 56 surrounds the forward portion of the rammer piston 54 with its rear end abutting against a forwardly facing shoulder formed by the enlarged portion 54a of the piston. The other end of the spring 56 extends forwardly and engages a vertical support plate 57 mounted in the housing 44.

A rammer pawl 58 is pivotally mounted on a pin 59 transversely supported on the enlarged portion 54a of the rammer piston. This pawl 58 is urged upwardly in a counterclockwise direction as viewed in FIG. 4a by a compression spring 60 which extends between the free end of the pawl and the cylinder enlargement 540. As can be seen from FIG. 5, the rammer pawl 58 extends upwardly into the receiver 26 through an elongated slot 62 formed in the lower wall of the receiver 26 between the depending lugs 26b. The pawl 58 engages the rear of the round of ammunition 28 when the rammer cylinder 54 is driven forwardly.

Still referring to FIG. 5, the rammer piston 54 is formed with a pair of outwardly extending ribs 54b on its opposite sides which slide within mating grooves in the housing sidewalls 44b. The grooves extend in a direction parallel to the barrel axis so that the rammer piston 54 will reciprocate on such a line.

It desired, a rammer sear may also be mounted on the backplate 49 as a safety device to prevent inadvertent firing of the rammer piston 54; however, for sake of simplicity, the sear is not shown in the drawings or described in detail herein.

d. Rammer Control Means In accordance with the invention, the movement of the deflector 38 is utilized to trigger the operation of the pneumatically powered rammer piston 54. For a description of the means responsive to movement of the deflector for initiating operation of the rammer, still refer to FIGS. 1 and 4a. The control rod 64 is mounted for longitudinal reciprocation on the top of the receiver aligned with the deflector tongue 38a. The forward end of the rod is positioned in the hole forming a bearing on the clamp 43 while portions of the remainder slide within an elongated guide tube 66 attached to the receiver. The forward end of the control rod is angled or beveled to form a cam surface 640 which cooperates with the notched surface on the rear portion of the deflector 38. The rear end of the rammer control rod engages a rammer valve 68 mounted on the top of the receiver 26 to control operation of the valve. Pressurized air is ducted into the rammer valve by means of an airline 70 connected to a source of pressurized air schematically shown in FIG. 24. The output line 72 of the rammer valve 68 is connected to the rear of the rammer tube 50.

For actuating the rammer control rod independently of the deflector, there is provided a cylinder 74 surrounding a central portion of the control rod 64 and mounted on the top receiver. The control rod has an enlarged portion forming a piston 64b which slides within the cylinder 74 and forms a working chamber 76 between its forward face and the surrounding walls of the cylinder. This chamber is connected to a pressurized air input line 78 mounted in the forward wall of the cylinder. Thus, the control rod 64 may be moved rearwardly by the application of air pressure to the working chamber 76. A coil spring 79 surrounds the control rod and extends between the rear face of the piston 64b and the rear of the cylinder 74 so that the rod is continually urged forwardly into engagement with the deflector. The connection of the control rod 64 to the rammer valve 68 is such that the rammer valve is normally closed when the control rod is in its forwardmost position.

e. Rammer Buffer Positioned within the forward portion of the housing 44 in line with the rammer piston 54 and the spring 56 is a buffer housing 80 having a closed forward end positioned in a forward plate 85 supported by the housing. An outwardly extending flange formed on the open rear end of the housing is clamped between the support plate 57 and adjacent slots in the housing 44 so that the housing is permanently fixed. A short buffer piston 82 is formed with an enlarged forward portion which slides within the housing 80 and a rear portion of reduced diameter which extends through the support plate 57 into the forward end of the rammer spring 56. Extending between the forward face of the buffer piston 82 and the closed forward end of the buffer housing 80 are a plurality of rings 84 arranged in the form of two concentric overlapping columns with the rings of each column being laterally aligned with the gap between adjacent rings in the other column. The diameters of the rings are such that each ring is normally slightly spaced from the adjacent rings in its column. Hence, the two columns of rings can be axially compressed somewhat, the inner column of rings receiving a compressing force radially inwardly and the outer column receiving a radially stretching force. Such an arrangement is capable of absorbing considerable force.

f. Barrel Sear Release Mechanism Still referring to FIG. 4a, there is shown beneath the buffer, a pneumatic cylinder 86 supported by the rear vertical plate 57 and the forward vertical plate 85. The rear of the cylinder 86 is tubular with a reduced diameter which extends through the plate 57. A pair of nuts 88 threaded onto the threaded end of the cylinder holds the cylinder fixed. An air line 89 extends through the ends of the cylinder and opens into the cylinder. Within the cylinder is a piston 90 attached to a rod 91 extending through the forward end of the cylinder. Attached to the forward end of the rod 91 is a release cam 92 having a forward cam surface 92a arranged to slope upwardly from its lower edge at approximately an angle of 45 towards its upper edge.

II. BARREL, BREECH RING AND BREECl-I BLOCK CAM ASSEMBLIES a. Barrel and Breech Ring Referring now to FIG. 4b for a description of the breech section of the gun, it can be seen that a barrel 13 in the barrel assembly 12 has a chamber 132 formed in its rear end for receiving a round of ammunition. Flutes 133 on the chamber walls reduce friction between the walls and a cartridge to facilitate ejection of the cartridge. The outer rear portion of the barrel is provided with a series of interrupted arcuate ribs 134 which mate with grooves between similar interrupted ribs 136 formed on the interior of a strong relatively massive breech member or ring 138. As can be seen in FIG. 10, the ribs are in three axially aligned sets that extend arcuately approximately 60 and are arcuately spaced 60. Thus, in assembly, the spaces of the breech ring are arcuately aligned with the ribs on the barrel so that the ring may be moved axially into the barrel. When the proper axial depth is reached, the ring 138 is rotated 60 so that the ribs 134 and 136 are arcuately aligned and interengaged as shown.

Referring to FIGS. 4b and 9, to lock the breech ring 138 to the barrel in this position, there is provided a barrel latch 140 pivotally mounted on a latch pin 142 supported by lugs 143 on the breech ring 138. A latch spring 144 extends between the rear 140a of the barrel latch and the breech ring, urging the barrel latch in a clockwise direction, as viewed in FIG. 4b, so that the massive forwarding depending lug 14% on the barrel latch fits within a notch 145 in the upper wall of the barrel immediately in front of the leading barrel rib 134a. In order to release the ring 138 from the barrel 13, it is necessary to depress the rear end 140a of the barrel latch 140 to pivot the forward end 140b upwardly.

b. Breech Block Cam The breech block cam assembly 16 includes a breech block cam 147 which is a generally U-shaped support member having, as seen from FIGS. 9, 10 and 12, a pair of axially extending grooves 148 formed in its sidewalls 149. Secured to the cam 147 within these grooves by suitable fasteners 153 (FIG. 2) are a pair of axially extending hardened tracks 151 each having a square cross section which mates with the grooves 148 and with grooves 152 formed in the lower rear portion 138a of the exterior of the breech ring 138. This track and groove arrangement slideably supports the weight of the barre] and breech ring assembly within the breech block cam assembly 16 for high-speed axial reciprocation.

c. Barrel Sear Mechanism Referring now to FIGS. 4b, 9 and 12, a barrel sear mechanism 129 releasably latches the barrel against axial reciprocation relative to the breech block cam. The barrel sear mechanism includes a sear lever 130 having bifurcated forward arms 130b. A transverse pin 180 extends through the arms 13% and through a cam block 182 which is secured to the bottom wall of the breech block cam 147 by suitable threaded fasteners 184. Springs 186 extend between the arms 130b of the barrel sear and the bottom wall 150 to urge the tongue 130a of the barrel sear upwardly, or in a clockwise direction, as viewed in FIG. 12. Each arm l30b of the barrel sear includes a sear surface 130d which faces rearwardly to engage notches 188 formed in the lower wall of the breech ring 138, as can be seen in FIG. 1 1. The scar surfaces 130d engage the notches 188 of the breech ring attached to the barrel to hold the barrel in its rearwardmost position when the gun is at rest.

It may be seen that the sloping cam surface 92a of the barrel sear release cam 92 engages the rearward tongue 130a of the barrel sear 130. Forward movement of the cam 92 depresses the tongue 130a causing the barrel sear 130 to pivot about the pin to release the breech ring 138 attached to the barrel 13.

d. Breech Block For opening and closing the end of the barrel chamber 132, there is provided a rugged breech block 190 having a shape which fits within the inverted U-shaped opening 191 in the breech ring 138, as can be seen from FIG. 11. The breech block 190 is mounted on a pin 192 which extends through vertically elongated openings 194 in the sidewalls of the breech ring 138 and further extend into elongated cam slots 196 formed in the sidewalls 149 of the U-shaped breech block cam 147. A pair of square shaped shoes 198 are mounted on the breech block pin 192 to support the pin slideably within the openings 194. On the outer ends of the breech block pin 192 are positioned a pair of rollers 200 which ride within the cam slots 196. The cam slots 196 are formed with a lower, rear, horizontally extending portion 1962, connected by a sloping intermediate portion 196C to a forward higher horizontally extending portion 196b. In the example of the invention illustrated, the portion 1960 is oriented at an angle of about 39 with respect to the horizontal. In view of this relationship, the

rollers 200 carrying the pin 192 and the breech block 190 are moved up and down by the cam slots 196 as the barrel is axially reciprocated.

In a plunger housing 146 formed integral with the breech ring 138 and located beneath the barrel, there is slideably positioned a plunger piston 209 attached to a piston rod 210, and a plunger compression spring 212 surrounding the rod 210 and urging the piston 209 rearward. A plunger link 214 having one end pivotally connected to piston 209 and its other end pivotally connected by a pin 215 to the base or bottom of the breech block 190, provides a constant force on the breech block in a clockwise direction as viewed in FIG. 4b. Or, in other words, the breech block 190 is constantly urged to pivot to a vertical position where it blocks or obstructs the entrance to the barrel chamber 132, and is in position to be moved by cam slots 196 to the upper position wherein the barrel chamber is locked or closed by the breech block.

The forward end of the plunger housing 146 is enclosed by an elongated cap 218 which covers the forward end of the piston rod 210 and a nut 211 mounted on the end of the rod. In FIGS. 4b and 9, the breech block 190 cannot be pivoted into its vertical blocking position in response to the urging of the plunger spring 212 because the upper edges 182a of the cam block 182 mounted on the wall 150 engage the breech block 190 so that the block is held in its horizontal position.

The cam block 182 is axially located slightly to the rear of the cam slot sloping surface 196a so that the breech block 190 is disengaged from the cam block 182 and is in a vertical position when the rollers 200 engage the sloping surface. Consequently, the breech block upper end may be received between the end of the barrel and a lug 219 depending from the rear upper edge of the ring 138. The breech block is thus locked in that position and the chamber 132 is blocked.

For detonating a round of ammunition, there is provided a hammer 224 which is pivotally mounted on the breech block pin 192 and centrally positioned within the breech block 190 in a space conforming to the shape of the hammer 224 as can be seen from FIG. 4b. The lower portion of the hammer is formed with an elongated slot 225 through which the link pin 215 extends. This causes the hammer to pivot with the breech block but permits limited pivoting of the hammer relative to, the breech block. Note in FIG. 9 that when the breech block is in its open position the hammer fits within the semicylindrical recess 182:: in the cam block 182.

The upper end of the hammer 224 is formed with an elongated tip 224a which extends through an aperture 190a in the breech block 190. As can be seen, the aperture 190a extends completely through the breech block and the length of the hammer tip 224a is such that it extends beyond the forward surface of the breech block when the hammer is pivoted into its most extreme position.

A spring 226 mounted within a socket in the breech block 190 engages the hammer 224 to urge the hammer in a counterclockwise direction so that its tip 224a does not extend beyond the forward surface of the breech block 190. The hammer tip 224a is, of course, axially aligned with the center of a round of ammunition when the breech block is in its chamber locking position so that the hammer is able to detonate the round of ammunition.

For tripping the hammer to strike a round of ammunition against the urging of the spring 226, the hammer is formed with a tongue 224b which when the breech block 190 is in its vertical position, is depending so that when the barrel reciprocates forward, the tongue engages a tubular inertia block 230. The block 230 is slideably mounted within a housing 232 secured to the bottom wall 150 of the fixed support member by suitable fasteners 233, as illustrated in FIG. 10. The inertia block 230 is urged forwardly by a compression spring 234 confined between a socket in the forward end of the inertia block 230 and a plug 236 threadably closing the forward end of the inertia block housing 232.

e. Extractor Also included in the breech ring assembly 14 is a cartridge extractor mechanism generally indicated at 360 in FIGS. 9 and 13. As can be seen from FIG. 9, the mechanism includes a pair of extractors 362 positioned on opposite sides of the breech ring 138, each of the extractors being provided with an inwardly extending tip 362a which fits within the groove 363a in the rear portion of a cartridge for a round of ammunition 363 schematically illustrated in FIG. 13. The extractor 362 includes a shaft 362b which extends through the sidewall of the breech ring 138, and an end 3620 (FIG. 11) which extends outwardly beyond the exterior of the breech ring.

An extractor lever 366 is fixed by a pin 364 to the end 362C of the extractor shaft. As best seen from FIGS. 11 and 13, the extractor lever 366 has a somewhat flattened triangular shape with its bottom wall having a depending portion 366a at its forward edge. The extractor lever is located so that it engages the upper surface 368 of the sidewall 149 of the breech block cam 147, FIGS. 2 and 12. This upper surface 368 has a forward portion 3680 which is slightly lower than a rearward portion 368b. The extractor lever 366 is vertically located such 5 that the lever is unaffected by the forward portion 368a of the upper surface 368; however, the rearward portion 368b being slightly higher causes the extractor lever to pivot so that the forward depending edge 366a and the rear edge 366b ride on the surface 368b.

To accommodate the injection of a round of ammunition into the barrel chamber 132, the extractor 362 and its shaft 364 is radially slideable outwardly as can be visualized from FIG. 9. A detent spring 370 and a cooperating detent 372 react against the inner surface of the breech ring 138 to urge the extractor inwardly. Reaction of the extractor tip 362a with the groove in a round being injected also pivots the extractor lever 366 so that the rear edge 366b does not ride on the forward portion 368a of the upper surface 368.

III DRIVE SPRING ASSEMBLY Still referring to FIG. 11, on the forward end of the breech ring 138 are formed a pair of large outwardly extending ears 156 each of which has an axially extending opening 157 therethrough and a smaller vertical aperture 158. As best seen from FIGS. 1 and 2, the leading or forward portion of the breech block cam 147 is formed with a pair of massive, upwardly extending ears 160 each having an axially extending opening. The breech ring assembly 14 and the breech block cam assembly 16 are interconnected by a pair of drive spring assemblies 17 in cooperation with the ears 156 and 160.

Referring to FIGS. 1 and 2, each drive spring assembly 17 includes a strong guide tube 162 having mounted thereon rugged, compression drive springs 164 which, in the example illustrated, are formed in three sections separated by spacers 165. A bushing 166 is mounted on the tube 162 with a cylindrical portion extending into the aperture in the ear 160 on the breech block cam 147. A flange on the forward end of the bushing 166 engages the forward face of the ear 160 and the rear end of the springs 164.

The rear end of the tube 162 extends into the aperture 157 (FIG. 11) in the ear 156 of the breech ring 138 and is secured thereto by a quick-disconnect pin 168 extending through the aperture 158 in the ear I56 and through the end of the tube 162.

The springs 164 are confined on the forward end of the tube 162 by a spacer 165 backed by a suitable nut 169 and a jam nut 170 threaded onto the tube. With this arrangement it can be seen that the guide tube 162 moves with the breech ring 138 and that the springs 164 are compressed between the car 160 and the nut 169 when the breech ring 138 is moved rearwardly relative to the breech block cam 147.

A bushing nut 171 threaded onto the rear end of the tube 162 serves to confine the bushing 166 and the springs 164 on the tube before assembly to the gun. The nut has an outer diameter which fits within the ear 160 so that the rear of the tube 162 carrying the nut 171 may be inserted into the ear 160 during assembly and then secured to the car 156.

The forward, unsupported end of the guide tube 162 terminates adjacent to a barrel sleeve 176 which is a convenient mounting surface for various mounting enclosures that may be employed for the gun, depending on the particular application. Also, with such enclosures, provision may be included for receiving the forward reciprocating end of the guide tube 162.

IV BUFFER-CHARGER ASSEMBLY Turning now to FIGS. 2, 3, and 4b, the buffer-charger assembly 22 is attached to the rest of the gun by means of a quick-disconnect pin 240 extending through a bracket 242 of the assembly and the forward end of the plunger cap 218. The bracket 242 is threaded to the end of a recoil piston rod 244 and further secured by a retaining ring 243. The rod 244 extends into a buffer housing 246 fixed to the support 24 by means of a flange 2460 (FIG. 1). The rod 244 is provided with a piston head 245 which slides within the housing slightly spaced from the housing walls, as can be seen from FIG. 3. The rear end of the buffer housing 246 is closed by a cap 248 and the forward end is closed by another cap 254.

Positioned within the buffer housing 246 on opposite sides of the piston head 245 are a pair of orifice sleeves 258a and 258b. These sleeves are formed with a tapered inner surface which decreases in diameter toward their respective ends of the housing. The housing 246 is normally filled with hydraulic fluid which must be displaced past the piston head as the head reciprocates within the buffer housing 246. The resistance to fluid flow increases as the piston head moves into the tapered section 258 so that the buffer provides increased buffering as the barrel approaches the ends of its stroke.

A plurality of Belleville springs 160 confined between the end cap 248 and the sleeve 1580 provide additional buffering effect. Similarly, Belleville springs 264 are confined between end cap 254 and the forward end of the orifice sleeve 258k.

In the event of minor leakage of hydraulic fluid from the buffer housing, a small supply of replenishing fluid may be provided in the tubular rear end (not shown) of the piston 244. The fluid may automatically be supplied through the use of a replenisher rod 272 which extends out of the rear end of the piston rod 244 and is slideably received in a bushing 274 which is attached to the rear end of the buffer piston 244 by means of a suitable retaining ring 276 as seen in FIG. 4b. The details regarding the replenishing are not disclosed herein since they are not necessary to an understanding of the claimed invention.

Referring to FIG. 3, threaded to the forward end of the housing cap 254 is a charger housing 280. A charger piston head 282 is threaded to the forward end of the piston rod 244 to slide within the charger housing 280. A compressed air inlet connection 284 is positioned in the forward end of the charger housing 280. A plurality of outlets (not shown) in the sidewalls of the charger housing between the charger piston 282 and the housing cap 254. Consequently, in the event of a misfire, pressure applied through the connection 284 against the forward end of the piston 282 forces the piston 244 rearwardly together with the barrel and breech ring.

v AMMUNITION FEED MECHANISM Refer now to the ammunition feed mechanism 20 which as previously mentioned is adapted to feed ammunition from either side of the rammer assembly 18 so that the gun may be fed two different types of ammunition as desired. As can be seen from FIGS. 2 and 5-7 the mechanism includes a large frame 290 which fits over the top and the two sides of the rammer assembly. The upper wall 32 of the frame mates with the upper portion of the rammer tube 26 to form, in effect, the upper wall for the portion of the rammer tube where a round of ammunition is inserted, as can be seen from FIGS. 2 and 4a.

Since the mechanism is symmetrical, only one side need be described in detail. As can be seen from FIGS. 6 and 7, there is a space 310 between sidewall 291 of the frame 290 and the rammer tube 26 sized to receive a belt of ammunition 312 for vertical feed movement. The rounds of ammunition 31 and 33 are carried by interconnected links 314, each having its outwardly extending edge portion 314a slideably received in a vertically extending slot 316 formed in the frame 290.

The belt of ammunition 312 is supported vertically by a pair of holding pawls 318. The rear holding pawl 318a engages the rear portion of a round of ammunition, as illustrated in FIG. 5 and in FIG. 2, while the forward holding pawl 318b engages a portion of reduced diameter on a round of ammunition as can be seen in FIG. 7. The holding pawls are pivoted to lugs 319 located on the outer sides of the wall 291, and they extend inwardly into the ammunition space 310 through openings formed in the wall. The portion of the frame defining the lower wall of the openings limits the downward or counterclockwise movement of the pawls 318 so that they are held at the oblique angle illustrated in FIG. 7 to support the best of ammunition 312. The free ends of the pawls 318 are pivotable upwardly to enable the belt of ammunition to be moved upwardly. Suitable springs (not shown) are associated with each pawl 318 to urge the free end of the pawl downwardly and in-' wardly to the position illustrated in FIG. 7.

Referring to FIG. 6 a feed slide 294 is slideably mounted to reciprocate vertically within the frame 290. The feed slide 294 is attached to a feed piston rod 297 carrying a piston confined within a cylinder 300 fixed on the wall 291. The feed slide 294 is powered upwardly within the slots 292 by applying air pressure to the underside of the piston within the cylinder 300 through suitable connections as shown in FIG. 24. Suitable springs 304, FIG. 2, urge the slide 294 downwardly when the air pressure is interrupted and suitable air exhaust means (not shown) may be provided.

A pair of feed pawls 305 pivotally attached to the feed slide 294 on each side of the feed slide extend into the ammunition space 310 in the path of the ammunition belt 312 to the position illustrated. When a downward force is applied to the inner end of a feed pawl 305, its lower outer end engages the inner sidewall of the feed slide 294 so that further downward pivoting movement is prevented. However, upward movement on the pawl pivots it out of the ammunition space 310 against the urging of the spring 308.

Referring now to FIGS. 5, 7 and 2, on either side of the feed slide 294 and the adjacent frame structure, there is mounted a pair of obliquely oriented cam levers 324, each having its lower end pivotally attached to the frame 290. Each cam lever 324 has a cam slot 326 which extends partially through the thickness of the lever from the feed slide side of the levers. Each cam slot has a lower portion 326a and a longer upper portion 326b, which is more vertically oriented than the lower portion when the lever 324 is at rest as illustrated in FIGS. 5 and 7.

Cam follower pins 328 carried by the feed slide guides 295 extend outwardly into the cam slots 326 in the cam levers 324. Consequently, when the feed slide 294 reciprocates vertically, the pins 328 are moved vertically and the engagement of the pins with the cam slots 326 causes the upper end of each lever 324 to pivot inwardly.

Pivotally attached to the upper end of each cam lever 324 is a side-stripping or delinking arm 330 having an inner end 330a which is curved to conform to the curvature of a round of ammunition 31 located at the height of the rammer tube 26 but positioned outwardly from the tube, as may be seen in FIG. 7. The arm is limited in its pivotal movement in the counterclockwise direction to the horizontal position illustrated in FIGS. 2, and 7, and a spring 331 attached to the sidestripping arm 330 and the cam lever 324 urges the sidestripping arm counterclockwise in the horizontal position. However, the side-stripping arm 330 is pivotable clockwise so that its inner end is movable upwardly through a slot 333 by a cartridge ofa round of ammunition.

Since the rammer tube 26 is open on both sides, it is desirable that a round of ammunition be prevented from moving laterally out of the rammer receiver in either direction. For this purpose, there is provided a pair of positioning pawls 332 pivotally mounted to the rear upper portion of the feed mechanism frame 290 as can be seen in FIGS. 2 and 5. These pawls are pivotable about axes extending parallel to the rammer receiver 26. As a round of ammunition is moved inwardly, the pawl 332 in the path of the round pivots inwardly until the round is centrally positioned. It then snaps downwardly and outwardly under a spring bias to the position illustrated in dotted lines in FIG. 5.

There is also provided a pair of positioning pawls 334 located more forward from the pawls 332 near the reduced diameter portion of a round of ammunition as illustrated in FIG. 7. Each pawl 334 is mounted to pivot about an axis 335 which is obliquely oriented, and the length of the pawl is such that the pawl 334 will pivot in a manner to cause its inner end to move both in a vertical and horizontal fashion. This is necessary since these pawls must pivot out of the transverse or lateral path of an incoming round of ammunition and out of the axial path of a round of ammunition being rammed forwardly towards the barrel. Also, each pawl 334 is provided with a suitable spring 336 urging the pawl to pivot into the holding position illustrated in FIG. 7.

VI PNEUMATIC CONTROL SYSTEM Refer now to the schematic illustration of FIG. 24 for a description of a pneumatic control system for operating the gun. As can be seen, there is included a source of pressurized air 342 having an output line 343 connected to a trigger valve 344 having its output line 345 connected to a feed control valve 348 which carries a sensing arm 349 that extends into the rammer tube 26. A first output line 350 from the feed control valve is connected to a feed selector valve 351 having two output lines 352 and 353 leading to the respective sides of the ammunition feed mechanism 20. Airline 352 is shown leading to the feed cylinder 300 containing the feed piston rod 297 carrying a second round of ammunition 31. When pressurized air is applied to the feed cylinder 300, the second round of ammunition 31 is moved upwardly toward the rammer tube 26. It will be understood from FIGS. 5, 6 and 7 a vertically moving round of ammunition replaces another round which is transversely thrust into the rammer tube 26.

The feed control valve 348 is provided with a second output line 70 connected to the rammer valve. Within the feed control valve 348, there is provided a suitable device for directing the pressurized air input to either one or the other of the two outlets, as controlled by a sensing arm 349 that extends into the rammer tube 26. By way of example, there is schematically illustrated a piston 354 mounted on the end of the rammer control arm 349, the piston being positioned and sized so that it closes the outlet to the feed selector valve 351 when there is a round of ammunition within the rammer causing the sensing arm 349 to be positioned as illustrated. A passage 355 through the piston 354 connects the air input line 345 to the second output line 70 leading to the rammer. When the piston 354 is in a second lower position, the outlet 350 is open to the inlet 345, and the output line 70 is blocked. A spring 356 positively urges the piston and control arm 349 downwardly although the piston is also urged ie this direction by he incoming air pressure since the exposed area on the upper surface of the piston is greater than that on the lower.

Branching from the output line 70 is a line 357 leading to a first round pulse and delay valve 346 which includes a floating piston 358 urged towards the upper end of a chamber within the valve 346 by a spring 359. Within the line 357 is a restricted orifice 360. The piston 358 is formed with an annular groove 358a around its periphery spaced from the ends of the piston. The air line 357 leading to the first round pulse and delay valve 346 is separated into a first section 3574 leading to the upper end of the valve, and a second section 357b leading to the side of the valve aligned with the annular groove 358a when the piston 358 is in its upper position. The air outlet 78 leading to the cylinder 74 mounted on the top of the gun receiver is aligned with the inlet section 3571). Hence, when the piston 358 is in its upper position as illustrated, the inlet 357b and the outlet 78 are in communication by way ofthe annular groove 358a.

A second outlet 362 from the first round pulse and delay valve 346 is spaced between the end of the valve and the outlet 78 so that it is closed by the piston 358 with the piston positioned as illustrated. The outlet 362 is connected to the barrel sear release cylinder 86.

The air supply 342 has another outlet 364 leading to a charger switch 366 which in turn is connected by a line 368 to the barrel charger 22.

VI OPERATION OF THE GUN While operation of the gun may be apparent from the foregoing structural description, a more thorough explanation follows. A discussion of the weapon cycle may be conveniently commenced with the gun as shown in FIG. 18. The breech ring assembly 14 is seared in its rear position by the sear 130, the rammer piston 54 is in its rear position due to the urging of the spring 56, and a round of ammunition 28 is positioned in the rammer tube 26. Upon operating the trigger valve 344 of the pneumatic control system shown ie FIG. 24, pressurized air is applied to the feed control valve 348. With the valve 348 positioned as shown in FIG. 24 pressure applied to the feed control valve 348 is transmitted through the passage 355 to the air line 70 leading to the closed rammer valve.

Pre'ssure in line 70 is also applied to branch line 357 leading to the valve 346. Section line 357k is initially in communication with the valve outlet line 78 through the annular groove 358a. Thus pressure is applied to the chamber 76 in the cylinder surrounding the control rod 64 and reacts against the forward face of the piston causing the control rod to move rearwardly against the resistance of the spring 79. The movement of the control rod 64 mechanically opens the rammer valve 68. As the rammer valve is opened by the control rod 64, the pressure applied through the line 70 passes through the rammer valve into the line 72 leading to the rammer tube 50. As explained above, application of pressure to the rammer tube 50 causes the rammer piston 54 to be fired forwardly causing the pawl 58 attached to the rammer cylinder to engage the rear of the round of ammunition 28 and ram the round forwardly towards the barrel 13, as illustrated in FIG. 19. As the round moves forwardly it engages the deflector depending projection 38d causing the deflector to pivot upwardly as shown in FIGS. 19 and 23. The projection 38d is provided to prevent the forward tip of the round from striking the deflector, which could cause damage to high explosive fuses.

As pressure is applied to the first round pulse and delay valve causing the control rod to actuate the rammer valve 68, pressure is also simultaneously applied through the line 357a to the end of the piston 358 in the first round pulse and delay valve 346. There is a very slight delay as the'piston 368 is moved downwardly against its spring 359, moving the annular passage 358a out of alignment with the inlet 345b and outlet 78, so that no further pressure is applied to move the rammer rod 64.

Downward movement of the piston 358 also opens the outlet line 362 to the high-pressure air with the result that pressure is applied to the barrel sear release cylinder 86. This pressure causes the cam 92 carried on the end of the piston rod 91 to be driven forwardly so that its end cam surface 92a transmits a force to the rear end 130a of the barrel sear 130. This action causes the sear 130 to pivot against the urging of the springs 186 (FIG. 12) causing the lug 130d to be removed from the notches 188 in the breech ring 138, thereby releasing the breech ring assembly 14 and the barrel assembly 12, as illustrated in FIG. 19. Releasing the barrel sear 130 causes the barrel assembly 12 to be driven forwardly under the impulse of the driving springs 164, thus starting the firing cycle shortly after the initiation of the ramming cycle. As the rammer piston 54 completes its forward stroke causing the round of ammunition to be propelled forwardly, the final forward movement of the rammer is stopped by the rings 83 in the rammer buffer 80.

When pressure is no longer applied through the air line 78 to the chamber 76 to hold the control rod 64 in its rearward position, the spring 79 urges it forwardly. However, when the round of ammunition 28 holds the deflector 38 in the position where it is pivoted upwardly as shown in FIGS. 19 and 23, the rear cam surface 38c of the deflector interferes with the forward surface 64a of the rod 64 causing the rod to be held in its rear position actuating the rammer valve 68, thus holding the valve open. Pressure is applied to the rammer piston 54 until the first round of ammunition 28 is moved out of the receiver to the point where the sensing rod 349 extending from the feed control valve senses the absence of a round and is moved downwardly by the spring 356, thus blocking the air line 70 leading to the rammer valve. As soon as this occurs, the rammer cylinder is returned to its rear position by its return spring 56, to the position illustrated in FIG 20.

After the round of ammunition 28 has moved beyond the deflector 38 into the firing chamber, the deflector is pivoted in a clockwise direction by its springs 41 to the position shown in FIG. 20 wherein the deflector blocks the forward end of the receiver 26. With the deflector in this position the rod 64 is free to move forwardly in response to the urging of its spring 79, thus enabling the rammer valve to be closed.

Downward movement of the piston 354 in the feed control valve 348 permits air pressure to be applied to the ammunition feed mechanism so that a second round 31 is fed into the receiver while the first round is being fired. Once in the receiver 26, the second round shifts the piston 354 upward so pressure is again applied to the rammer valve 68. Due to the restricted orifice 360 in the air line 357, the momentary shifting of the piston 354 does not cause the pressure on the first round pulse and delay valve to fall enough to allow its piston 358 to move upwardly and allow pressure to be applied to the control rod 64.

While this rammer and feed operation is occuring, the firing cycle is continuing with the forward travel of the breech ring assembly 14 and barrel assembly 12. The breech block 190 slides forwardly beyond the cam block 182 and is then free to pivot about the breech block pin 215 due to the force of the plunger spring 212 upon the breech block acting through the piston 208 and the link 214. As shown in FIG. 20 the breech block is almost pivoted to a position wherein it obstructs or closes the barrel chamber 132. The round 28 has, of course, already entered the chamber.

Further forward motion causes the breech block 190 to move upward, finally chambering the round and locking the breech block, as shown in FIG. 21. This upward motion is accomplished by the breech block pin 192 and its rollers 200 following the path of the cam slots 196. More specifically, the rollers move from the rear portion 1960 up the sloping portion 196a to the upper forward portion l96b of the cam slots. The upper portion of the breech block 190 thus moves in front of the depending lug 219 on the breech ring so that the block is locked in position closing the barrel chamber 132. It should be noted from FIG. 20 that the breech block has not moved upwardly by the cam slots 196 and that the breech block has been released by the cam block 182 so that it is pivoting out of its horizontal position into its vertical or blocking position.

The hammer 224 moves with the breech block 190. Just after final locking of the breech block, the tongue 22417 of the hammer 224 strikes the spring-biased or yieldable inertia block 230, pivoting the hammer about the breech pin 215 as permitted by the elongated slot 225 and driving the forward tip 224a of the hammer forwardly to sharply strike the primer of the chambered round, as shown in FIG. 21, thereby causing ignition. The shell 29 leaves the cartridge 28a and speeds forward as shown.

The barrel assembly 12 and the breech assembly 14 continue to travel forward a short distance due to their momenturn and the continued urging of the drive springs 164 until the recoil force caused by ignition of the round overcomes the forward momentum and reverses the direction of movement. As the recoiling parts now move rearward, the breech block rollers 200 along with the breech block pin I92 and the breech block follow the breech block cam slots 196 downward, drawing the breech block out of its locking recess in front of the lug 219 on the breech ring 138, and unlocking is accomplished, as shown in FIG. 22. The complete unlocking time has been arranged to minimize chamber gas leakage and to provide sufficient residual force to properly eject the expended case 28a.

With the recoiling parts moving to the rear just after the instant of the unlocking of the breech block 190, the extractor levers forward portions 266a engage the sloping surface 3680 of the breech block cam assembly support member, causing the levers to pivot quickly, together with the extractors 362 FIGS. 9 and 13). This movement of the extractors gives an initial sharp extraction force to the cartridge case through the annular groove 28b formed on the case 28a of FIG. 21, should it be needed. However, it should be noted that mechanical extraction is normally not required since the use of the fluted chamber 132 allows the cartridge case to be ejected easily from the barrel.

The breech block 190 now begins to pivot open, first by the gas pressure acting on the cartridge head, and then by its lower end striking the cam block 182, which action cams the breech block 190 to its horizontal or full open position and compresses the plunger spring 212. Once the breech block 190 has pivoted out of the way, the cartridge case 28a is blown clear of the chamber 132, past the breech block 190, and it strikes the case deflector 38 which deflects the case upwardly through the outlet 27 clear of the weapon, as illustrated in FIG. 22.

As the recoiling parts near the end of their rearward movement, they are first slowed and then stopped by the action of the buffer assembly 22 (FIG. 3). The buffer piston 245 is also moved rearwardly within the fixed buffer housing 246, as seen in FIG. 4b. Normal buffer operation is accomplished by the buffer piston approaching the rear tapered sleeve 258a in the buffer housing. This tapered sleeve 258a forms a variable area orifice with the area decreasing in the direction of travel of the piston so that hydraulic fluid is throttled around this area. Extra buffer capacity is provided by the stack of Belleville springs 260 in the event this is necessary. Note that the rod 272 can extend into the inertia block housing plug 236.

It should be mentioned at this point that buffering on the forward stroke is provided by the tapered sleeve 258b within the buffer housing 246 in the same manner described above. This is necessary in the event of a misfire where a round does not fire when struck by the hammer, or in the event the breech block is closed on an empty chamber.

It should also be noted that during the central portion of the stroke of the buffer piston 244 in its housing 246 the area between the piston and the housing forms a velocity sensitive constant area orifice which limits the maximum velocity of the recoiling parts. 

1. An automatic gun comprising: a barrel having a firing chamber; a rammer for driving a round of ammunition into the firing chamber; an expended cartridge ejection port adjacent the firing chamber; and means in the path of an ejected cartridge responsive to ejection of the cartridge for initiating operation of said rammer so that a round is started toward the chamber as the expended cartridge of the previous round is being ejected.
 2. The gun of claim 1 wherein said last recited means includes: a deflector which is struck by an ejected cartridge causing the cartridge to be deflected away from the gun, said deflector being movable by the ejected cartridge; and means responsive to movement of the deflector caused by the ejected cartridge for initiating operation of the rammer.
 3. The gun of claim 2 wherein: the rammer is operated by pressurized fluid; and the means responsive to movement of the deflector includes a control rod which operates a valve controlling the application of pressurized fluid to the rammer.
 4. The gun of claim 3 including: means operated by fluid pressure for actuating said control rod independently of movement by the deflector.
 5. The gun of claim 2 including: an ammunition receiver positioned to the rear of the barrel having a tubular portion aligned with the barrel for guiding a round of ammunition toward the barrel firing chamber; and the deflector being positioned between the forward end of the receiver and the firing chamber.
 6. The gun of claim 1 including: an ammunition receiver positioned to the rear of the barrel having a tubular portion aligned with the barrel for guiding a round of ammunition toward the barrel chamber, the rammer being arranged to advance a round from the receiver to the chamber; a rammer valve actuated by said last recited means for controlling the energization of said rammer; a mechanism for feeding ammunition into said receiver; a feed control valve having an inPut connected to an energizing source and a first output leading to said feed mechanism and a second output leading to said rammer valve; a sensing element extending into the receiver for sensing the presence or absence of a round of ammunition within the receiver, the sensing element being connected to control the operation of the feed control valve in a manner such that the output from the feed control valve is applied to the rammer valve when the sensing element senses the presence of a round of ammunition in the receiver and the output is applied to the feed mechanism when the sensing element senses the absence of a round of ammunition within the receiver.
 7. The gun of claim 1 including: means for operation of said rammer independently of said means responsive to cartridge ejection to start ramming of the first round of a series of rounds.
 8. The gun of claim 7 wherein: said barrel is mounted for axial reciprocation; and including spring means for driving said barrel forwardly; a barrel sear for holding the barrel in a rearward position; and means for releasing said barrel from its sear shortly after said rammer is operated by said independent rammer initiating means so that said first round is propelled into the barrel as the barrel is moving forwardly under the urging of said spring means.
 9. An automatic gun comprising: a barrel having a firing chamber; a receiver having a tubular portion aligned with the barrel for guiding a round of ammunition toward the barrel chamber; an expended cartridge ejection port intermediate the receiver tubular portion and the barrel; a rammer mounted on the receiver for reciprocation to advance rounds from the receiver tubular portion toward the barrel chamber; a deflector disposed between the ejection port and the receiver tubular portion, and mounted for movement from the first position obstructing the path between the barrel chamber and the receiver tubular portion for deflecting ejected cartridges out the ejection port, to a second position clear of said path to permit passage of a round of ammunition travelling from the receiver tubular portion to the barrel chamber, said deflector being movable when struck by an expanded cartridge being ejected; and means responsive to the deflector movement caused by an expanded cartridge for actuating the rammer to advance a round of ammunition from the receiver toward the barrel chamber.
 10. The gun of claim 9 wherein: the rammer is adapted to be driven forwardly by pressurized fluid; and the responsive means includes a valve for controlling the application of pressurized fluid to the rammer, and a control rod positioned to be moved by the deflector for operating said valve.
 11. The gun of claim 10 including: a mechanism for feeding ammunition to said receiver, the mechanism including a fluid operating feed piston; a feed control having an input connected to a pressurized air supply and a first output leading to said feed piston and a second output leading to the rammer valve; a sensing element extending into the receiver for sensing the presence or absence of a round of ammunition within the receiver, the sensing element being connected to control the operation of the said feed control valve in a manner such that the output from the feed control valve is applied to the rammer valve when the sensing element senses the presence of a round of ammunition in the receiver and the feed control valve output is applied to the feed mechanism piston when the sensing element senses the absence of a round of ammunition within the receiver.
 12. The gun of claim 9 wherein: said deflector is pivotally mounted to pivot between said first and second positions and slideably mounted to be moved when struck by an ejected cartridge; said means responsive to the deflector movement includes a control rod slideably mounted on the receiver with the forward end of the rod positioned to be engaGed by a portion of the deflector as the deflector is moved towards the rod, and a valve for controlling the application of pressurized fluid to the rammer for driving the rammer, the control rod being connected to operate the valve when moved by the deflector.
 13. The gun of claim 12 including: a control rod actuator comprising a piston formed on the control rod, and means surrounding the piston to define a working chamber adjacent the forward face of the piston so that by the application of pressurized fluid to the chamber and the forward face of the piston the rod may be moved to control the valve independently of the deflector.
 14. The gun of claim 9 wherein: said responsive means includes a valve for controlling the application of pressurized fluid to the rammer to drive the rammer, and a control rod positioned to be moved by the deflector for operating said valve; and including a fluid operated control rod actuator for moving said control rod independently of movement by the deflector; means for mounting said barrel for axial reciprocation; spring means for urging said barrel forwardly; a barrel sear for holding said barrel in its rear position; a fluid operated barrel sear release actuator for moving the sear to release the barrel; and a first round pulse and delay valve for controlling the application of pressurized fluid to said control rod actuator moving the control rod, and for operating the barrel sear release actuator, in such a manner that when a first pulse of fluid pressure is applied to the first round pulse and delay valve, pressure is immediately applied to the means for moving the control rod and pressure is initially delayed and then applied to the barrel sear release actuator whereby the rammer is driven forwardly slightly before said barrel is released for forward movement.
 15. The gun of claim 14 wherein said round pulse and delay valve includes: a cylinder; a piston within the cylinder biased to one end of the cylinder by a spring, means defining a fluid passage extending across the piston spaced from said one end of the cylinder; the cylinder having a first fluid inlet and a first fluid outlet connected by said passage when the piston is biased by the spring to said one end of the cylinder, the outlet being connected to the means for moving the control rod; the cylinder having a second fluid inlet in one end for applying fluid to the end of the piston to move the piston in opposition to the spring, and a second fluid outlet in the side of the cylinder spaced between said one end of the cylinder and said first outlet so that the second inlet and outlet are in communication only after the piston has been moved away from said cylinder end sufficiently to open the second outlet, the second outlet being connected to said barrel sear release actuator, said passage being moved out of communication with the first inlet and outlet when the piston is moved sufficiently to permit communication between the second inlet and outlet.
 16. The gun of claim 9 including: means for actuating said rammer independently of movement by the deflector.
 17. An automatic gun comprising: a barrel having firing chamber; a receiver having a tubular portion aligned with the barrel for guiding a round of ammunition toward the barrel chamber; an expended cartridge ejection port intermediate the receiver tubular portion and the barrel; a rammer mounted on the receiver for reciprocation to advance rounds from the receiver tubular portion toward the barrel chamber; deflector mounting means mounted for slideable axial reciprocation on the top forward portion of the receiver adjacent the ejection port; a deflector pivotally mounted on said deflector mounting means, the deflector being urged by spring means to a first position extending downwardly to obstruct the path between the barrel chamber and the receiver tubular portion for deflecting ejected cartridges out of the eJection port, and the deflector being pivotable to a second position clear of said path to permit passage of a round of ammunition traveling from the receiver tubular portion to the barrel chamber, said deflector mounting means carrying the deflector being slideable rearwardly when struck by an expended cartridge being ejected; and means responsive to the rearward deflector movement for actuating the rammer to advance a round of ammunition from the receiver toward the barrel chamber. 